The polymorphism of CLOCK gene rs4864548 A>G is associated with susceptibility of Alzheimer’s disease in Chinese population

The aim of this study was to investigate the correlation between polymorphism of circadian locomotor output cycle kaput (CLOCK) gene rs4864548 A/G and susceptibility of Alzheimer's disease (AD). A total of 296 unrelated AD patients and 423 control subjects were enrolled in the case-control study. Genotypes of apolipoprotein E (APOE) and CLOCK gene rs4864548 A/G were determined by a Polymerase Chain Reaction (PCR) restriction fragment length polymorphism detection method. Our results showed that in the whole sample or APOE epsilon 4 non-carriers, prevalence of A carriers in CLOCK gene rs4864548 A/G in AD patients was remarkably higher than that in control subjects (in the whole sample: chi(2) = 47.614, p < 0.0001; in APOE epsilon 4 non-carriers: chi(2) = 22.493, p < 0.0001). However, among APOE epsilon 4 carriers, the difference in the prevalence of A carriers in CLOCK gene rs4864548 A/G between AD patients and controls was no statistically significant (chi(2) = 0.669, p = 0.379). These findings demonstrate that A carriers in CLOCK gene rs 4864548 A/G were closely related to a high susceptibility of AD among APOE epsilon 4 non-carriers while the functional polymorphism of CLOCK gene rs4864548 A/G was not associated with the susceptibility of AD among APOE epsilon 4 carriers.